Hammond Pole a bunch of ***********s?

An account was settled, in full and advised to this company 04.12.2017. Today, I received an email stating"We have now been instructed by our client to obtain a Judgment for non-payment of this account. This process will also incur additional legal and collections costs for which you are liable. You are required to conclude an acceptable repayment arrangement by 2018-03-07 16:00 in order to suspend the legal process." the amount quoted is way less than was settled IN DECEMBER and I have tried all day [08.03.2018 which is hen I received the email] to contact this company. I have yet to hear from anyone in this regard. Why are they quick to threaten but slow to react now? How come, MONTHS after settlement was made, the money has obviously not been allocated. If their systems were as amazing as they advertise, how has this happened? If I was the client I would be seriously concerned about the matter in which they are conducting collections on my behalf.